Double-walled tank container

ABSTRACT

The present invention concerns a double-walled tank container ( 1, 12, 13, 14 ) whereby the inner container ( 2, 3 ) is stored at the bottom inside the outer enclosure ( 6 ) by a spacer consisting of several spacer pieces ( 16 ). The spacer provided, which is preferably placed near a front saddle ring ( 12, 13 ), imparts transportation and storage stresses between the inner tank ( 2, 3 ) and the outer enclosure ( 6 ) and consequently between the inner container ( 2, 3 ) and the frame ( 14 ) of the tank container. The spacer ( 16 ) can be laid out in such a way that it absorbs shocks and/or defines a hollow space ( 10 ). This hollow space can serve as a thermal insulation or for the installation of temperature equalization devices, mediums or a leak detector fluid.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present patent application claims priority from German PatentApplication No. DE 202 15 657.5, filed on Oct. 11, 2002.

[0002] Certain applications require the use of double-walled tankcontainers. In this case, an inner container is more or less completelyenclosed by an outer container. These designs are necessary when thecontainer needs to be extremely leak-proof, such as, for example, whenthe interior plate is brittle and the inner tank requires a high degreeof protection against exterior impacts, or needs to be completelyprotected by a liquid temperature equalization medium. The leak-proofcharacter often needs to be further increased by filling the spacebetween the outer and inner tank with a non-hazardous test liquid thusrevealing possible leaks in both the inner as the outer tank

[0003] It is expedient that the outer containers of such tank containerscan be incorporated in proven and standardized frame constructionscustomary for single-walled containers. Ring saddle mountings, such asdescribed in DE 32 12 696 C2, have proven to be worthwhile in the fieldof tank containers. In this design, the tank is connected with the frontframes via the vaulted end arcs of the tank. This construction enablesthe stress between the tank and the frame, which occurs during handlingand transportation of the tank containers, to be completely imparted.Other connections between the tank and the frame are generally notnecessary.

[0004]FIG. 4 shows a known design of a front ring saddle mounting on adouble-walled container, whereby a front ring (12′) runs through theexterior bottom plate (8′, 8″) and is welded to the interior bottomplate (3′). This requires separating the exterior bottom plate andrunning a piece (8′) around the interior bottom plate (3′) back to thefront ring (12′), as well as mounting an exterior bottom piece (8″) inthe front ring (12″). This procedure is unsatisfactory from a productionviewpoint and unsuitable for inner containers with a brittle interiorbottom plate since the stresses from transportation and handlingdirectly work on the tank plate covered with the coat. Increasing thewall thickness of the entire inner container, or at least the end bottomplates of the inner container, can offset this. This would increase theweight of the tank considerably.

[0005] Furthermore, this design does not guarantee that the containerwill be leak-proof and increases the production cost. The front ring(12′) needs to be interrupted in the area where it is connected with theinterior bottom plate in order to enable the hollow space (10′) insidethe front ring to interconnect with the hollow space (10′) outside thefront ring, and to allow a leakage detector liquid to run through it.Furthermore, there is a risk that a leak (3″) in the area of the weldingbetween the front ring (12′) and the interior bottom plate is not shownbecause possible double sheet metal plating (12″) in the front ringmight cause the leak to seep out through the exterior bottom plate (8′,8″) without activating the leakage detector.

[0006] The present invention aims at fastening an inner tank in thedefined position in an outer enclosure, enabling stresses and strains tobe imparted between the inner tank and the frame without having tointerrupt the outer enclosure in the strain transmission areas.Furthermore, it aims at realizing low-cost production measures toleak-proof the container, and making light inner containers with brittleinterior coats available for tank containers.

[0007] The solution to this problem consists of a tank container asdescribed in claim 1 whereby the inner container is fixed lengthwiseinside an outer container connecting the latter to the front frame in aconventional way with a front ring saddle mounting. Since the vaultedinterior and exterior bottom plates have a process tolerance, it isimpossible to install the inner container inside the outer containerwithout compensating these process tolerances. The spacer also solvesthis problem.

[0008] The enhanced design in accordance with claim 2 makes it easier toinstall the outer tank around the inner tank.

[0009] claims 3 and 4 cover extremely expedient designs and layouts ofthe spreader(s) for ring saddle mounted tank containers. Spacerscomposed of several spacer blocks allow for a very precise tolerancecompensation between the interior and exterior bottom plates. Theconical design not only compensates the stresses running in thedirection of the tank axle, but also radial and vertical stresses, andimparts them to the front ring mounted directly between the interior andthe exterior bottom plates in accordance with claim 4.

[0010] claim 5 covers an enhanced design whereby the inner tank does nothave to be completely encompassed by the outer tank. This is the casewhen the outer tank serves as a leakage safety device and therefore onlyneeds to reach the maximum filling height of the inner tank.

[0011] claim 6 covers a tank container whereby the outer enclosurecompletely encompasses the inner enclosure and the connections attachedto the inner enclosure can penetrate the outer enclosure. The designdescribed in claim 7 covers putting a leak detector liquid or a heatingor cooling medium in the hollow space allowing a thorough rinse of theclearance.

[0012] The designs covered by claims 8 and 9 mainly concern tankcontainers with a coated inner container. In this case, shock-absorbingspacers connect the inner container with the outer container.High-resistance PUR/PIR foams especially allow for a very smooth stresstransition in the inner container. Filling the space between the innerand the outer tanks with foam enhances this effect, and allows forextremely thin-walled, light yet coated inner containers. For this, theouter container needs to be closed completely. The design described inclaim 10 allows for the installation of a heating element between theinner and outer enclosure. This requires appropriate spacers arerequired. The heating element either heats the inner tank directly orthe temperature medium between the inner and outer enclosure.

[0013] The drawings below illustrate preferred construction examples. Inthese drawings:

[0014]FIG. 1 shows a partial side view of a tank container according tothe invention with a schematic presentation of the front frame.

[0015]FIG. 2 shows a detail of the front ring saddle mounting accordingto the invention.

[0016]FIG. 3 shows a side view of the tank container end with a coatedinner tank and shock-absorbing spacers.

[0017]FIG. 4 shows a detailed view of a conventional front ring mountingof a double-walled container.

[0018] According to the invention shown in FIG. 1, the end of thecontainer has a double-walled tank 1 with an inner tank composed of acylindrical center section 2 and an interior bottom plate 3 connectedvia the welding 4. Both the tank section 2 and the interior bottom plate3 are concentric with respect to the tank axle 5. Furthermore, thedouble-walled tank has an outer enclosure 6 encompassing a cylindricalsection 7 and an exterior bottom plate 8. Both parts 7, 8 are alsoconcentric with the tank axle 5 and are connected via the welding 9.

[0019] The cylindrical section 7 presented only partially encompassesthe tank section, thus keeping the apex area uncovered. This design isexpedient when the inner container 2, 3 only needs to be encompassed upto its maximum filling height instead of being encompassed completely.The clearance 10 between the inner tank 2, 3 and the outer tank 7, 8 iswelded shut.

[0020] A cylindrical front ring 12 and a corner iron saddle ring 13connect the exterior bottom plate 8 with the frame (not shown) equippedwith a front frame 14. Welded joints 15 a through 15 f (FIG. 2) connectthe front frame 14, saddle ring 13, front ring 12 and the exteriorbottom plate 8.

[0021] Spacer pieces 16 create the clearance between the exterior bottomplate 8 and the interior bottom plate 3. A conical arrangement of therings makes the spacers concentric with respect to the tank axle of theouter surface of the interior bottom plate 3 and the inner surface ofthe exterior bottom plate. The spacers are located in the area of thewelded joints 15 e and f, thus allowing the stress imparted over thefront ring 12 to be imparted through the exterior bottom plate over thespacer pieces 16 on the interior bottom plate 3. Thanks to the conicalarrangement, the stress can be imparted in the direction of the tankaxle, as well as in a radial direction of the tank axle. The designexample shows spacer pieces 16 attached with spot welding to theinterior bottom plate 3. It is also possible to attach the spacers tothe inner surface of the exterior bottom plate 8.

[0022] The size of the spacer pieces 16 determines the size of thehollow space 10 and also offsets the process tolerance of the interiorand exterior bottom plates 3, 8 in such a way that the inner tank 2, 3is clamped between the exterior bottom plates.

[0023] When the tank container is in use, the hollow space 10 serves asa leakage control devise. For this purpose, the hollow space 10 iscompletely filled with a harmless test liquid and connected in aninterconnecting way with a compensator reservoir (not shown) placedabove the apex of the tank. The connection in the apex of the tank (notshown) is laid out in a shell type arrangement 7 c. The filling level ofthe compensator reservoir can be checked through an inspection glass oran extra level indicator. In case of a leakage in the inner tank 2, 3,the test liquid enters the inner tank and the gauge in the controlreservoir drops. Changes in the filling level are determined withregular checkups or by an audio and/or video signal.

[0024] The hollow space 10 can also be used for the circulation of aliquid or gaseous temperature equalization medium. The temperature ofthis medium is controlled by a connected aggregate (also not shown).

[0025]FIG. 3 shows a design with very thick spacer pieces 16 a creatinga very large hollow space 10. These spacer pieces 16 a consist of ashock-absorbing material (high resistance PUR/PIR, elastomers, plastics,etc.) creating an energy absorbing, buffering elastic force couplingbetween the inner tank 2, 3 and the outer enclosure. In the pictureddesign, the cylindrical section 7 of the outer enclosure 6 completelyencompasses the inner tank 2, 3 and is composed of the referencecylinder shell segments 7 a and 7 b, welded together and to the exteriorbottom plate 8 in an overlapping design. This layout is extremelysuitable for inner tanks 2, 3 with a brittle interior coat (not shown)necessary for very aggressive freights. The elastic floating arrangementof the inner tank 2, 3 in the outer enclosure 7 a, 7 b, 8 avoids strainscausing rips in the coat. The hollow space 10 may be additionally filledwith so-called high-resistance PUR/PIR. This increases the protectivecapacity of the inner tank 2, 3. At the same time, this creates aconsiderable thermal insulation effect, which is very useful for thetransportation or storage of temperature equalized freights.

[0026] A possible design for this type of freight consists of atemperature equalization unit installed in the hollow space 10 betweenthe inner tank 2, 3 and the outer enclosure 6. This temperatureequalization unit could be made of half pipes, a resistance heatingelement or other temperature control devices welded to the inner tank.Other variants on the proposed invention can consist of using one singlespacer as a conical ring or a concave disk between the interior bottomplate 3 and the exterior bottom plate 8 instead of individual spacerpieces 16. This is useful in long containers to impart stresses in aradial direction to the tank axle 5 between the inner tank 2, 3 and theouter enclosure 6.

[0027] The shock-absorbing spacer pieces 16 a may also come asliquid-filled cases or flexible tubing for construction with a verylarge hollow space 10. With this type of spacer pieces 16 a and fillingof the hollow space 10, the inner container 2, 3 can be stored so safelythat it can even be made of a brittle material such as glass.

1. Tank container with a double-walled tank (1) connected on both sidesby a vaulted interior and exterior bottom plate (2, 8), whereby theouter tank enclosure (6) is connected with a frame (14), characterizedby a spacer placed on one end between the exterior bottom plate (8) andthe interior bottom plate (3).
 2. Tank container as described in claim1, whereby the spacer is attached (in particular welded or glued) toeither the interior or the exterior bottom plate (3, 8).
 3. Tankcontainer as described in claim 1, whereby the spacer is composed ofseveral spacer pieces (16, 16 a) and/or is placed in a conical ringarrangement concentric with respect to the tank axle and following theexterior of the interior bottom plate and the interior of the exteriorbottom plate, respectively.
 4. Tank container as described in claim 1,whereby the spacer is located inside a front ring (12), which is part ofa front saddle mounting (12, 13) and connected with the exterior bottomplate (8).
 5. Tank container as described in claim 1, whereby thecylindrical section of the outer enclosure (7) between the exteriorbottom plate (8) and the inner tank (2, 3) encompasses only in part in alower area.
 6. Tank container as described in claim 1, whereby the outerenclosure (6) completely encompasses the inner tank (2, 3) and isattached to the inner tank (2, 3) only with spacers.
 7. Tank containeras described in claim 1, whereby the hollow space (10), which is definedby the spacers or spacer pieces (16, 16 a), between the outer enclosure(6) and the inner tank (2, 3) is filled with a test liquid or atemperature equalization medium.
 8. Tank container as described in claim1, whereby spacers or spacer pieces (16, 16 a) made of a shock-absorbingmaterial and the hollow space (10) between the inner tank (2, 3) and theouter enclosure (6) are filled with a second material. The firstmaterial includes in particular of high-resistance PUR/PIR, elastomersand plastics, and the second material includes of PUR/PIR border foams.9. Tank container as described in claim 1, whereby the interior of theinner tank (2, 3) is equipped with a coat, in particular a phenolicresin or vitreous enamel coat, or the inner tank (2, 3) is made of abrittle material, in particular glass.
 10. Tank container followingclaim 1, whereby the clearance between the inner and outer enclosure isequipped with a temperature equalizing devise.